Which container runtime engine is used by default in OpenShift?

OpenShift uses a container runtime engine to manage and run containers within its Kubernetes-based environment. Let’s analyze each option:

A. containerd

Incorrect:

Whilecontainerdis a popular container runtime used in Kubernetes environments, it is not the default runtime for OpenShift. OpenShift uses a runtime specifically optimized for Kubernetes workloads.

B. cri-o

Correct:

CRI-Ois the default container runtime engine for OpenShift. It is a lightweight, Kubernetes-native runtime that implements the Container Runtime Interface (CRI) and is optimized for running containers in Kubernetes environments.

C. Docker

Incorrect:

Docker was historically used as a container runtime in earlier versions of Kubernetes and OpenShift. However, OpenShift has transitioned to CRI-O as its default runtime, as Docker's architecture is not directly aligned with Kubernetes' requirements.

D. runC

Incorrect:

runCis a low-level container runtime that executes containers. While it is used internally by higher-level runtimes likecontainerdandcri-o, it is not used directly as the runtime engine in OpenShift.

Why CRI-O?

Kubernetes-Native Design:CRI-O is purpose-built for Kubernetes, ensuring compatibility and performance.

Lightweight and Secure:CRI-O provides a minimalistic runtime that focuses on running containers efficiently and securely.

JNCIA Cloud References:

The JNCIA-Cloud certification covers container runtimes as part of its curriculum on container orchestration platforms. Understanding the role of CRI-O in OpenShift is essential for managing containerized workloads effectively.

For example, Juniper Contrail integrates with OpenShift to provide advanced networking features, leveraging CRI-O for container execution.